A field may be arranged with a generally circular perimeter or circular region where plants or crops are cultivated. For example, a field with a generally circular perimeter or circular region may be irrigated by a pivot irrigation system. An operator of an off-road vehicle may manually steer the vehicle to track the circular perimeter, or an arc of the circular perimeter to load a field boundary into a guidance computer for the off-road vehicle. In practice, the operator may use visual cues or one or more reference markings in an attempt to track the circular perimeter. Although the operator of the off-road vehicle could manually drive the entire circular perimeter to load a field boundary into the guidance computer, such task can be tedious, time-consuming, and prone to error. Accordingly, there is a need for a method for guiding an off-road vehicle along a curved path, such as indicating to the operator when the arc driven by the operator is sufficient to accurately and reliably estimate the remainder of the circular perimeter and/or its center point.